Method of treatment of attention deficit/hyperactivity disorder (adhd)

ABSTRACT

The invention comprises a method for treatment of ADHD or ADHD-related disorders by a pharmaceutical agent exhibiting combined serotonergic or noradrenergic reuptake transporters and monoamine receptor activity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.15/615,423, filed Jun. 6, 2017, which is a Continuation of U.S.application Ser. No. 14/634,281, filed Feb. 27, 2015, which is aContinuation of U.S. application Ser. No. 13/930,051, filed Jun. 28,2013, which is a Continuation of U.S. application Ser. No. 12/585,157,filed Sep. 4, 2009, which claims priority from U.S. ProvisionalApplication No. 61/094,502, filed Sep. 5, 2008. The entire contents ofthe aforementioned applications are incorporated herein by reference.

BACKGROUND

Viloxazine (Emovit®, Vivalan®, Vivarin®, Vicilan®) is a bicyclicantidepressant morpholine derivative that inhibits the reuptake ofnorepinephrine. Viloxazine hydrochloride has been approved in Italy,Belgium, England, Ireland, Germany, Portugal, Spain, the formerYugoslavia, France, Slovakia, for the treatment of major depressivedisorder.

Viloxazine is known to inhibit noradrenergic reuptake transporters (155nM) and has very weak activity at the serotonin reuptake inhibitor (17.3μm). (Tatsumi et al [1997] Eur J Pharmacol 340 (2-3): 249-58).

The present invention is predicated on the unexpected discovery thatviloxazine may be effective in the treatment of ADHD in humans withnominal, if any, significant side effects.

SUMMARY OF THE INVENTION

In one embodiment of the invention, a method of treating ADHD andADHD-related disorders in a mammal comprising administering to themammal a pharmaceutical agent exhibiting 5HT1B and/or 5HT7 antagonisticactivity is provided.

In another embodiment, the invention provides a method for treatment ofADHD and ADHD-related disorders in a mammal comprising administering tothe mammal a pharmaceutical agent exhibiting a combination of at leasttwo of the following: noradrenergic reuptake inhibitory activity, 5HT1Bantagonistic activity, and 5HT7 antagonistic activity.

In yet another embodiment, the invention provides a method for treatmentof ADHD and ADHD-related disorders in a mammal comprising administeringto the mammal a pharmaceutical agent exhibiting a combination of atleast two of the following: noradrenergic reuptake inhibitory activity,α4/β2 antagonistic activity, and α7 antagonistic activity.

In still another embodiment, the invention provides a method fortreatment of ADHD and ADHD-related disorders in a mammal comprisingadministering to the mammal a pharmaceutical agent exhibiting acombination of at least two of the following: 5HT1B antagonisticactivity, 5HT7 antagonistic activity, α4/β2 antagonist activity, and α7antagonistic activity.

In another embodiment, the current invention provides a novel method fortreatment of ADHD and related disorders by administering a formulationof viloxazine.

The invention also provides a method of identifying compounds for thetreatment of ADHD and/or similar disorders.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a competition curve obtained with compound viloxazine withhuman 5-HT7 receptor.

FIG. 2 shows the agonist effect of the compound viloxazine with human5HT7 receptor.

FIG. 3 shows the antagonist effect of the compound viloxazine with human5HT7 receptor.

FIG. 4 shows a competition curve obtained with compound viloxazine withhuman 5-HT1B receptor.

FIG. 5 shows the agonist effect of the compound viloxazine with human5HT1B receptor.

FIG. 6 shows the antagonist effect of the compound viloxazine with human5HT1B receptor.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise specified, “a” or “an” means “one or more.”

In one embodiment, the invention provides a method for treatment of ADHDand ADHD-related disorders. ADHD-related disorders include, but are notlimited to, mood or affective disorders such as anxiety, depression orbipolar disorder; or disorders where ADHD may be a co-morbid syndrome,such as obsessive compulsive disorder, Tourette's Syndrome, or PostTraumatic Stress Disorder. The method comprises the administration to amammal diagnosed with ADHD or an ADHD-related disorder a pharmaceuticalagent exhibiting a combination (at least 2) of: noradrenergic reuptakeinhibitory activity, 5HT1B antagonistic activity, and 5HT7 antagonisticactivity. In another embodiment, the invention comprises a method oftreating any of the above-listed disorders with a pharmaceutical agentexhibiting a combination (at least 2) of: noradrenergic reuptakeinhibitory activity, α4/β2 antagonistic activity, and α7 antagonisticactivity. In still another embodiment, the invention comprises a methodof treating any of the above-listed disorders with a pharmaceuticalagent exhibiting a combination (at least 2) of: 5HT1B antagonisticactivity, 5HT7 antagonistic activity, α4/β2 antagonistic activity, anda7 antagonistic activity.

The pharmaceutical agents suitable for invention are identified by aprocess comprising the steps of: (1) selecting one or a combination ofactive agents with known activity inhibiting either serotonin ornoradrenergic reuptake transporters; (2) conducting a receptor screeningassay on the selected agent(s) to identify activity on at least onenicotinic, dopaminergic, serotonergic or gabaergic receptor or bindingsite where the activity is known to be associated with ADHD;(3)determining if said activity is agonistic or antagonistic; (4) selectingamong the screened active agents at least one that targets the most ofthe different types of ADHD-associated receptors; and (5) optimizing thetotal dosage of the selected active agent(s).

In a preferred embodiment of the invention, the pharmaceutical agent isviloxazine. The present inventor unexpectedly discovered that inaddition to noradrenergic activity, viloxazine exhibits specificantagonist activity at the 6-HT7 (serotonin 7) and 5HT1B receptors. Itwas also discovered that viloxazine exhibits α4/β2 and/or α7antagonistic activity. This heretofore unknown receptor activity ofviloxazine was evaluated as follows:

I. Viloxazine activity on 5-HT receptors

A heterologous competition assay was used to determine the relativeaffinity of viloxazine for 5-HT receptors. Briefly, recombinant 5-HT1BOR 5-HT7 receptors were expressed in a CHO cell line. The receptors werethen saturated with a tritiated receptor-specific ligand atconcentrations known to be saturating. Thereupon, 10 μM viloxazine wasadded to the cells in the presence of non-specific ligand and incubated.In this way, viloxazine was allowed to “compete” with thereceptor-specific ligand, such that greater displacement (i.e., %inhibition) is indicative of greater binding strength of viloxazine at agiven receptor. “Specific binding” refers here to the difference in thebinding of the ligand to the receptors in the presence or absence of anexcess of the viloxazine. The conditions and results of the assays aresummarized in the Table 1.

TABLE 1 Conditions of the displacement assay at select serotoninreceptors for viloxazine Receptor Ligand Conc. Non-specific Incubation %Inhib. Detection method 5-HT1A (h) [3H]8-OH-DPAT 0.3 nM 8-OH-DPAT (10μM) 60 min/22° C. 66 Scintillation counting 5-HT1B [125I]CYP (+30 0.1 nMserotonin (10 μM) 120 min/37° C.  78 Scintillation counting μM(−)propranolol) 5-HT1D [3H]serotonin 1 nM serotonin (10 μM) 60 min/22°C. 18 Scintillation counting 5-HT2A (h) [3H]ketanserin 0.5 nM ketanserin(1 μM) 60 min/22° C. −17* Scintillation counting 5-HT2C (h)[3H]mesulergine 1 nM RS-102221 (10 μM) 60 min/37° C. 56 Scintillationcounting 5-HT3 (h) [3H]BRL 43694 0.5 nM MDL 72222 (10 μM) 120 min/22°C.  18 Scintillation counting 5-HT4e (h) [3H]GR 113808 0.3 nM serotonin(100 μM) 60 min/37° C. 16 Scintillation counting 5-HT5A (h) [3H]LSD 1 nMserotonin (100 μM) 60 min/37° C. 15 Scintillation counting 5-HT6 (h)[3H]LSD 2 nM serotonin (100 μM) 120 min/37° C.   6 Scintillationcounting 5-HT7 (h) [3H]LSD 4 nM serotonin (10 μM) 120 min/22° C.  70Scintillation counting *A negative number reflects negligibleinhibition, i.e., a condition where the binding of the radioactive testligand was greater in the presence of viloxazine. This reflects eitherthe variability in the radioactive control ligand binding orfacilitation by the test ligand.

The affinity of viloxazine for 5-HT7 5-HT1B receptors was furthercharacterized by determining the IC50 (i.e., the concentration ofviloxazine that can inhibit 50% of control specific binding). For thisexperiment, a range of viloxazine concentrations was selected for theligand blocking assay. The IC50 was determined using non-linearregression analysis of the competition curves using a Hill equationcurve fitting

(Y=D+[(A−D)/(1+(C/C50)nH)],

where Y=specific binding, D=minimum specific binding, A=maximum specificbinding, C=compound concentration, C50=IC50, and nH=slope factor). Theinhibition constants Ki were calculated using Cheng Prusoff equation. Kiis defined as the concentration of the competing ligand (viloxazine)that bound to half the binding sites at equilibrium in the absence ofradioligand or other competitors. The results of the affinity assay aresummarized in Tables 2 and 3, and in FIG. 1.

TABLE 2 % of Control Specific Binding Receptor Concentration(M) 1st 2ndMean 5-HT1A (h) 3.0E−08 97.8 99.8 98.8 1.0E−07 93.8 96.9 95.4 3.0E−07104.7 110.3 107.5 1.0E−06 104.8 109.1 107.0 3.0E−06 76.5 71.4 73.91.0E−05 32.5 41.3 36.9 3.0E−05 21.9 19.6 20.7 1.0E−04 5.3 5.8 5.5 5-HT1B3.0E−08 102.0 99.9 101.0 1.0E−07 97.6 92.4 95.0 3.0E−07 92.4 82.7 87.61.0E−06 77.7 79.0 78.4 3.0E−06 61.5 52.6 57.1 1.0E−05 36.6 27.1 31.93.0E−05 13.7 4.5 9.1 1.0E−04 −10.4 −12.4 −11.4 5-HT2C (h) 3.0E−08 97.9125.8 111.9 1.0E−07 116.6 111.5 114.0 3.0E−07 92.9 102.7 97.8 1.0E−06108.2 104.2 106.2 3.0E−06 90.6 91.9 91.3 1.0E−05 61.6 63.1 62.3 3.0E−0533.1 36.6 34.8 1.0E−04 8.4 14.3 11.4 5-HT7 (h) 3.0E−08 90.6 92.7 91.71.0E−07 102.9 94.2 98.5 3.0E−07 80.4 85.1 82.7 1.0E−06 73.5 66.5 70.03.0E−06 48.2 60.2 54.2 1.0E−05 27.3 27.9 27.6 3.0E−05 15.3 13.2 14.31.0E−04 6.5 8.1 7.3

TABLE 3 Summary of IC50 determination at select serotonin receptors forViloxazine. Reference Assay compound IC50 (M) Ki (M) n(H) 5-HT1A (h)8-OH-DPAT 7.1E−06 4.5E−06 1.3 5-HT1B serotonin 3.8E−06 2.3E−06 1.05-HT2C (h) RS-102221 1.4E−05 6.4E−06 1.0 5-HT7 (h) serotonin 3.2E−061.2E−06 0.8

The nature of the binding (i.e., agonist or antagonist) was nextdetermined. Briefly, an assay was designed that examined the agonisteffect on the 5HT7 or 5-HT1B receptor, i.e., the generation of cAMP orthe blockade of this effect when stimulated by a 5HT7 agonist,serotonin. This was also done with a range of concentrations todetermine the relative agonist versus antagonist binding Ki. The EC50values (concentration producing a half-maximal specific response) andIC50 values (a concentration causing a half-maximal inhibition of thecontrol-specific agonist response) were determined by a non-linearregression analysis of the concentration-response curves generated withmean replicate values using Hill equation curve fitting. The apparentdissociation constants for antagonists Kb were calculated using themodified Cheng Prusoff equation.

The conditions of the screening are represented in Table 4. Results ofthe functional assays are seen in FIGS. 2 (5-HT7 agonist assay) and 3(5-HT7 antagonist assay). The agonist assay demonstrated no measurableresponse (FIG. 2). The antagonist assay for 5-HT7 yielded a weakresponse with an IC50 greater than 3.0×10−5 M.

TABLE 4 Conditions for 5HT7 Functional Assay Reference IncubationReaction Method of Assay compound conditions product detection 5-HT7 (h)none 45 min/37° C. cAMP HTRF (agonist effect) 5-HT7 (h) serotonin 45min/37° C. cAMP HTRF (antagonist effect) 5-HT1B (h) none 30 min/37° C.cAMP HTRF (agonist effect) 5-HT1B (h) serotonin 30 min/37° C. cAMP HTRF(antagonist effect)II. Viloxazine activity on nicotinic receptors

Conditions for the initial screen:

Membrane homogenates of rat cerebral tissue are incubated with 1.5 nM[3H]cystine (for nicotinic acetylcholine α4β2 screen) or 1 nM[1251]α-bungarotoxin (for nicotinic acetylcholine α7 screen) in theabsence or presence of 10 μM test compound in buffer. Nonspecificbinding is determined in the presence of 10 μM nicotine for α4β2 or 1 μMα-bungarotoxin for α7. Following incubation, the samples are filteredrapidly under vacuum through glass fiber filters and rinsed severaltimes. The filters are dried, then counted for radioactivity in ascintillation counter. The results can be expressed as a percentinhibition of the control radioligand specific binding. The standardreference compound is nicotine for α4β2 and α-bungarotoxin for α7, whichis tested in each experiment at several concentrations to obtain acompetition curve from which its IC50 can be calculated. Conditions forthe IC50 determination can be the same as for the initial screen, exceptthe test compound is assayed at 8 different concentrations between 10-9and 10-4 M.

The effectiveness of viloxazine for ADHD treatment can be evaluated in aFive-Choice Serial Reaction Time Task (5-CSRTT) assay. This test intypically performed with rats and is designed to show brain regions andneural substrates involved in attention, information processing speed,impulsivity, hyperactivity and preservative behaviors (obsessivecompulsive disorder-like). Pharmaceutical agents of the currentinvention, including but not limited to viloxazine, can be tested tomeasure their effects on attention, impulsivity and reaction time andthe outcome analyzed to determine their profile and application totreating ADHD.

An additional test, SmartCubeTM, can also be performed to obtain a“behavioral signature” for a given compound. The experimental platformof this test combines robotics, computer video capture and analysis(called computer vision), and bioinformatics to capture and analyzedata.

An animal treated with the test compound under study is placed in anenclosure and presented with a non-invasive behavioral challenge, suchas changing the floor's configuration. The animal's behavior is recordedusing cameras and electro-mechanical sensors, and data from theserecordings are processed using algorithms to reveal the compound'sbehavioral signature. This “signature” can then be screened against thecompany's database of signatures from reference compounds to identifycandidates predicted to have utility in treating ADHD.

According to the invention, ADHD or ADHD-related disorders can betreated in human subjects by administering viloxazine in a total dailydose that is at least 10% lower than the current minimally effectivedose of 2.14 mg/kg, which is used to treat major depressive disorder. Inother embodiments, the dose is 15% lower, 25% lower, 35% lower, or 50%lower than the current dose. Dosage ranges of 1.1 mg/kg/day to 9.7mg/kg/day or approximately 20 to 800 mg for pediatric (aged 6 to 17) andadult population are also provided.

According to the invention, viloxazine can be administered in the amountof from 10 to 600 mg/day. In another embodiment, the daily dose ofviloxazine may be from 150 to 400 mg/day. In yet further embodiment ofthe invention, viloxazine is administered in the amount of up to 300mg/day. The method of the current invention offers a safe and effectivetreatment of ADHD and related disorders in both children and adults. Forthe purposes of this invention, a term “viloxazine” includes viloxazineand all pharmaceutically acceptable salts thereof, as well as allisomers, stereomers and polymorphs thereof.

In another embodiment, the invention encompasses a method of treatmentof ADHD or ADHD-related disorders with viloxazine that is characterizedby an improved adverse effect profile. The adverse effects that arediminished by the method of the present invention include, but are notlimited to, nausea, vomiting, insomnia, loss of appetite, increasederythrocyte sedimentation, EKG and EEG anomalies, epigastric pain,diarrhea, constipation, vertigo, orthostatic hypotension, edema of thelower extremities, dysarthria, tremor, psychomotor agitation, mentalconfusion, inappropriate secretion of antidiuretic hormone, increasedtransaminases, seizure, and increased libido. Hence, the inventivemethod provides for the treatment of ADHD without, or at least with farless frequency than with conventional viloxazine-treatment, of one, two,six or more of these listed side effects. The efficacy and the adverseeffect profile of the lower dose treatment of the current invention canbe evaluated in a randomized, placebo controlled trial.

Whereas particular embodiments of the invention have been describedherein for the purpose of illustrating the invention and not for thepurpose of limiting the same, it will be appreciated by those ofordinary skill in the art that numerous variations of the details,materials and arrangement of parts may be made within the principle andscope of the invention without departing from the invention as describedin the appended claims.

Although the foregoing refers to particular preferred embodiments, itwill be understood that the present invention is not so limited. It willoccur to those of ordinary skill in the art that various modificationsmay be made to the disclosed embodiments and that such modifications areintended to be within the scope of the present invention.

All of the publications, patent applications and patents cited in thisspecification are incorporated herein by reference in their entirety.

REFERENCES

1. Vanhoenacker P, Haegeman G, Leysen JE. 5-HT7 receptors: currentknowledge and future prospects. Trends Pharmacol Sci 2000;21(2):70-7.

2. Lucchelli A, Santagostino-Barbone MG, D′Agostino G, Masoero E, ToniniM. The interaction of antidepressant drugs with enteric 5-HT7 receptors.Naunyn Schmiedebergs Arch Pharmacol 2000;362(3):284-9.

3. Hedlund PB, Huitron-Resendiz S, Henriksen SJ, Sutcliffe JG. 5-HT7receptor inhibition and inactivation induce antidepressant like behaviorand sleep pattern. Biol Psychiatry 2005;58 (10):831-7.

4. Giles H, Lansdell HJ, Bolofo ML, Wilson HL, and Martin GR.Characterization of a 5-HT_(1B) receptor on CHO cells: functionalresponses in the absence of radioligand binding. Br J Pharmacol 1996:117:1119-26.

What is claimed is:
 1. A method of treating a patient suffering fromADHD, consisting of administering to the patient in need thereof atherapeutically effective amount of viloxazine.
 2. The method of claim1, wherein the therapeutically effective amount is from about 20 toabout 800 mg a day.
 3. The method of claim 1, wherein thetherapeutically effective amount is from about 100 to about 600 mg aday.
 4. The method of claim 3, wherein the therapeutically effectiveamount is from about 150 to about 400 mg a day.
 5. The method of claim4, wherein the therapeutically effective amount is from 150 to 300 mg aday.
 6. The method of claim 1, which provides an improved adverse effectprofile.
 7. The method of claim 1, wherein the patient is a human child.8. The method of claim 1, wherein the patient further suffers fromanxiety, depression, or bipolar disorder.
 9. The method of claim 1,wherein the patient further suffers from obsessive compulsive disorder,Tourette's Syndrome, or Post Traumatic Stress Disorder.